Prof. Aaron Bufe

Research

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My research focuses on the physical and chemical processes that control the evolution of landscapes, the erosion, transport, and deposition of sediments, and the global fluxes of nutrients and carbon. To this end, I combine field observations with analogue experiments, geochronological methods, and geochemical analyses of sediment, soil, and water.

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Chemical weathering in floodplains

Chemical weathering of silicate rocks sequesters 0.1 gigatons of carbon per year from the atmosphere. It compensates for CO2 emissions from the solid Earth and stabilizes Earth’s climate. Half of the global weathering may occur in sediments that are stored on floodplains. Yet, we do not have a framework to quantify floodplain weathering or predict its sensitivity to climate and tectonics.

Using the geochemical analyses of water and sediments, we quantify how much carbon is sequestered by weathering on the associated floodplains. Together with ongoing work on organic-carbon cycling on floodplains, a mechanistic understanding of these weathering processes will help us predict the role of floodplains in Earth’s carbon cycle through geologic time.

Running projects

• Floodplain Weathering - FloW

Dosch, Sophia; Hovius, Niels; Bufe, Aaron; Repasch, Marisa; Scheingross, Joel; Vieth-Hillebrand, Andrea; Sachse, Dirk (2024): CO2 fluxes driven by floodplain morphology and seasonality at the Rio Bermejo, Argentina. GFZ Data Services. https://doi.org/10.5880/GFZ.4.6.2024.004

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Time- and spatial scales of sediment storage, erosion and transport

Rivers move over 15 billion tons of sediment and about one billion tons of dissolved solutes per year across Earth’s continents. These fluxes shape landscapes, generate sedimentary archives, and modulate Earth’s climate. Using field data and large-scale experiments, we measure and model how (fast) rivers build valleys and channel belts and how sediments transition through these river corridors. We also aim to understand how rivers react and adapt to changes in climate and erosion rates.

Running projects

• Floodplain Weathering - FloW

Turowski, J. M., McNab, F., Bufe, A., and Tofelde, S.: Width evolution of channel belts as a random walk, Earth Surf. Dynam., 13, 97–117, https://doi.org/10.5194/esurf-13-97-2025, 2025.

Tofelde, S., Bufe, A., & Turowski, J. M. (2022). Hillslope sediment supply limits alluvial valley width. AGU Advances, 3, e2021AV000641. https://doi.org/10.1029/2021AV000641

Bufe, Aaron & Turowski, Jens & Burbank, Douglas & Paola, Chris & Wickert, Andrew & Tofelde, Stefanie. (2019). Controls on the lateral channel‐migration rate of braided channel systems in coarse non‐cohesive sediment. Earth Surface Processes and Landforms. 44. 2823-2836. 10.1002/esp.4710.

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The role of mountains in earths carbon cycle

The uplift and erosion of mountain ranges alters atmospheric CO2 concentrations. Modelling the net effect of this mountain building on the carbon cycle over geologic timescale remains challenging, because many different processes are involved. For example, metamorphism of carbonates deep within the crust can generate CO2 that is emitted to the atmosphere through volcanoes or in hotsprings. In turn, the weathering of minerals and organic carbon that are exposed to earth’s surface by erosion can both emit or sequester atmospheric CO2. To quantify the long-term impact of mountains on Earth’s carbon cycle and climate, we measure erosion and weathering rates under different tectonic and climatic boundary conditions. These datasets can be used to model Earth’s climate evolution over millions of years.

Bufe A, Rugenstein JKC, Hovius N. CO2 drawdown from weathering is maximized at moderate erosion rates. Science. 2024 Mar 8;383(6687):1075-1080. doi: 10.1126/science.adk0957. Epub 2024 Mar 7. PMID: 38452079.

Erlanger, E., Bufe, A., Paris, G. et al. Deep CO2 release and the carbon budget of the central Apennines modulated by geodynamics. Nat. Geosci. 17, 465–471 (2024). https://doi.org/10.1038/s41561-024-01396-3

Bufe, A., Hovius, N., Emberson, R. et al. Co-variation of silicate, carbonate and sulfide weathering drives CO2 release with erosion. Nat. Geosci. 14, 211–216 (2021). https://doi.org/10.1038/s41561-021-00714-3

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The riverine carbon cycle under climate changes

Human-induced climate change has a measurable impact on terrestrial carbon fluxes. Major attention has been devoted to quantifying changes in terrestrial and marine organic carbon cycling. However, warming also impacts inorganic carbon fluxes – particularly those associated with rock weathering. In collaboration with international partners, we measure temporal changes in weathering and carbon fluxes as recorded by rivers. Our work focuses on mountainous and cryospheric landscapes that experience above-average warming and where thawing permafrost exposes minerals and old organic carbon to weathering.

Running projects

In collaboration with the National Natural Science Foundation of China: https://www.nsfc.gov.cn (Grant No. 42401095: Quantification and mechanisms of old carbon in CO2 emissions from typical permafrost rivers on the Qinghai-Tibet Plateau) and National Science Foundation for Young Scholars of China (Grant No. 42303058 – Sulfide weathering and its impact on the carbon cycle in tectonically active regions)

Xu et al., 2025, Climate warming and strengthened hydrologic cycle accelerate CO2 release from rock weathering, Geochimica et Cosmochimica Acta 2025 Vol. 407 Pages 174-192 https://doi.org/10.1016/j.gca.2025.09.006

Sen Xu, Si-Liang Li, Aaron Bufe, Marcus Klaus, Jun Zhong, Hang Wen, Shuai Chen, and Li Li, Escalating Carbon Export from High-Elevation Rivers in a Warming Climate,
Environmental Science & Technology 2024 58 (16), 7032-7044, DOI: 10.1021/acs.est.3c06777

Publications